The myelin sheath that covers many cns axons is formed by oligodendrocytes.
Oligodendrocytes are type of neuroglia (non-neural cells found in central nervous system) with protective, trophic and supportive role. Their function is to insulate axons (with myelin sheath), in the central nervous system (CNS) which is, equivalent to the function performed by Schwann cells in the peripheral nervous system (PNS).
So you don’t know any of them?
Due to the ionic bonding of the molecules that allow for the geometric/crystalline structure.
The aorta is connected to the left side of the heart and carries blood full of oxygen to the rest of the body
Answer:
The correct answer is - option A is continuous variation that follows a geographic continuum.
Explanation:
A cline is a slow change in the physical and genetic traits of a population or species across a geographical difference or gradient. If a species present in a very large area, there would be some members live on different environmental condition in comparison to others.
By this gradient members of species show continuous variation that follows a geographic continuum. For, example, In a species of warm-blooded animals have large body size in cooler area than in warmer area.
Thus, the correct answer is - option A is continuous variation that follows a geographic continuum.